This application claims the priority of German Application No. 19916966.7, filed Apr. 15, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electronic ignition starter switch and steering wheel locking apparatus for a motor vehicle, and for passenger cars. Steering wheel locks of this generic type provide an immobilization function in that they keep the steering wheel locked unless the vehicle user has used an appropriate authentication means to verify that he is authorized to drive. The steering wheel locking unit is coupled, via appropriate coupling means, to the ignition starter switch unit, so as to ensure that the steering wheel locking unit is in its unlocked state during starting of the engine.
In an apparatus of this type, the ignition starter switch unit is formed by a mechanical ignition key/ignition lock system, in which the ignition lock can be operated by a key which authorizes driving. In this case, the ignition lock may be rotated, in a known manner, between four positions, namely a xe2x80x9c0xe2x80x9d position in which the key can be inserted and removed and both the ignition and the vehicle power supply are switched off, a xe2x80x9c15Rxe2x80x9d position in which the vehicle power supply is activated but the ignition is still switched off, a xe2x80x9c15xe2x80x9d position in which the ignition is switched on and in which the ignition lock is in the normal driving mode, as well as a xe2x80x9c50xe2x80x9d position, to which the ignition lock is briefly rotated in order to start the engine.
The steering wheel locking unit, including a locking control unit and an actuating unit is supplied via a supply line. The steering wheel locking unit is in the locked state when no power supply is present, and can be changed to its locked state by supplying the necessary operating power. The supply line is routed via a rotatable ignition lock, which acts as a mechanical switching element. In this case, it keeps the supply line closed as long as, after successful key authentication, it has not been rotated through more than a threshold-value angle, which can be predetermined, from its off position so that the steering wheel locking unit can remain in its locked state during this period. When the ignition lock is moved beyond the predetermined threshold-value angle, it interrupts the supply line, thus ensuring that the steering wheel locking unit is in its unlocked state during the subsequent starting of the vehicle engine.
German Patent Specification DE 196 34 627 C1 describes the coupling of a steering wheel locking unit to an electronic immobilizer, in which the steering wheel locking unit has a bolt as an actuating element, whose movement between an unlocked position and a locked position is blocked by means of a blocking device when the electronic immobilizer is armed. When the electronic immobilizer is disarmed, the blocking device releases the bolt, which can then be moved to its unlocked position, for example by the head of a vehicle key, by a separate transponder or by a Bowden cable. Alternatively, the bolt can be operated by rotating an ignition key that has been inserted into an ignition lock, as is known from German Laid-Open Specifications DE 44 34 587 A1 and DE 44 46 613 A1, which are cited in DE 196 34 627 C1.
Purely electronic ignition starter switch units without any mechanical ignition key/ignition lock system are being increasingly used in modern passenger cars, in particular systems without any active key operation, that is to say so-called xe2x80x9ckeyless-goxe2x80x9d systems, in which a closure system and an electronic immobilizer are controlled via wire-free communication by means of an authentication element, for example in the form of a smart card, which for this purpose just needs to be carried by the user, without any further action being required of him. In such systems, the ignition starter switch unit typically does not contain any mechanical key/lock unit, but corresponding push-button switches, to switch the ignition on and off and to start the engine. On the other hand, for these systems, it is also desirable to have the capability to prevent a steering wheel locking unit which is present still accidentally being in its locked state when the vehicle engine is running.
German Patent Specification DE 197 41 438 C1 describes a method and a control system for stopping a motor vehicle, in which the motor vehicle propulsion engine is switched off, and the vehicle speed is detected when the ignition starter switch is switched off; the associated speed sensor then continues to operate at least until it indicates that the vehicle is stationary. Any steering lock that is fitted is then activated only after the sensor identifies that the vehicle is stationary.
One object of the present invention is to provide a relatively simple ignition starter switch and steering wheel locking apparatus, which ensures that the steering wheel locking unit is in its unlocked state when the vehicle engine is running.
This and other objects and advantages are achieved by the ignition starter switch and steering wheel locking apparatus according to the invention, in which the steering wheel locking unit and the ignition starter switch unit are coupled to one another via a coupling means, the latter comprises state interrogation and starting blocking means, which interrogate the locking state of the steering wheel locking unit and allow the vehicle engine to be started only when the steering wheel locking unit is in its unlocked state. The state interrogation and starting blocking means are thus able to interrogate the locking state of the steering wheel locking unit when the vehicle user demands that the engine be started and, following this, to allow the demanded engine start actually to be carried out only if the steering wheel locking unit is in the unlocked state.
This ensures that the steering wheel locking unit is in its unlocked state once the engine has been successfully started and while the vehicle is being driven, without necessarily switching to this state, for example by interrupting a supply line, by the ignition starter switch unit, before the engine is allowed to start. The apparatus is thus suitable not only for traditional driving authorization systems with a mechanical ignition lock, but also for the xe2x80x9ckeyless-goxe2x80x9d systems and other driving authorization systems without any mechanical ignition lock. Furthermore, in the event of a fault in which, although the steering wheel locking unit receives an unlocking command to assume its unlocked state, this control command is acted upon because of a system fault, it is advantageous to block the starting of the engine since the state interrogation identifies that the steering wheel locking unit is incorrectly in the locked state.
In a further development, the state of the steering wheel locking unit is interrogated by an ignition starter control unit in the ignition starter switch unit. This is accomplished by connecting the ignition starter control unit via an appropriate interrogation line to the steering wheel locking unit, specifically to a locking control unit, which drives an associated actuating unit for locking and unlocking the vehicle steering element. Thus, when the vehicle user demands that the engine be started, the ignition starter control unit is actually able to either allow or prevent the starting process, depending on the result of the interrogation of the state of the steering wheel locking unit. If the said control units are used as system components, the only extra item needed is the interrogation line.
In a further refinement, a supply line is provided, by to which the steering wheel locking unit can be supplied with two different power levels. A first, higher power level is chosen such that it is sufficient to supply both the locking control unit and the actuating unit, for example an actuating motor. The second, lower power level is chosen such that, although it is sufficient to operate the locking control unit, it is not sufficient to operate the connected actuating unit. When the second power level is applied to the steering wheel locking unit, its locking control unit functions so that it can be interrogated by the ignition starter control unit to determine the locking state of the steering wheel locking unit. At the same time, the locking actuating unit does not operate owing to the lack of a sufficient power supply which, if a conventional system design is chosen, means that the steering wheel locking unit is in the unlocked state. In order to change the steering wheel locking unit to its locked state, the higher power level is applied to the supply line. In a further refinement the need for a separate interrogation line between the steering wheel locking unit and the ignition starter switch unit has been eliminated, since the supply line for the steering wheel locking unit is routed via the ignition starter switch unit, and at the same time acts as the state interrogation line.